US20240004235A1 - Optical display device module and optical display device comprising same - Google Patents

Optical display device module and optical display device comprising same Download PDF

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Publication number
US20240004235A1
US20240004235A1 US18/247,318 US202118247318A US2024004235A1 US 20240004235 A1 US20240004235 A1 US 20240004235A1 US 202118247318 A US202118247318 A US 202118247318A US 2024004235 A1 US2024004235 A1 US 2024004235A1
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United States
Prior art keywords
retardation layer
optical display
polarizer
layer
display module
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US18/247,318
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English (en)
Inventor
Bong Choon KIM
Jun Mo Koo
Kwang Ho Shin
Jung Hun YOU
Sang Hum LEE
Eun Sol CHO
Seon Oh HWANG
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Samsung SDI Co Ltd
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Samsung SDI Co Ltd
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Assigned to SAMSUNG SDI CO., LTD. reassignment SAMSUNG SDI CO., LTD. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: CHO, EUN SOL, HWANG, SEON OH, KIM, BONG CHOON, KOO, JUN MO, LEE, SANG HUM, SHIN, KWANG HO, YOU, Jung Hun
Publication of US20240004235A1 publication Critical patent/US20240004235A1/en
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    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G02F1/133634—Birefringent elements, e.g. for optical compensation the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/133528—Polarisers
    • G02F1/133531—Polarisers characterised by the arrangement of polariser or analyser axes
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1337—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers
    • G02F1/133746—Surface-induced orientation of the liquid crystal molecules, e.g. by alignment layers for high pretilt angles, i.e. higher than 15 degrees
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2413/00—Indexing scheme related to G02F1/13363, i.e. to birefringent elements, e.g. for optical compensation, characterised by the number, position, orientation or value of the compensation plates
    • G02F2413/02—Number of plates being 2
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F2413/00—Indexing scheme related to G02F1/13363, i.e. to birefringent elements, e.g. for optical compensation, characterised by the number, position, orientation or value of the compensation plates
    • G02F2413/08—Indexing scheme related to G02F1/13363, i.e. to birefringent elements, e.g. for optical compensation, characterised by the number, position, orientation or value of the compensation plates with a particular optical axis orientation

Definitions

  • the present invention relates to a module for an optical display and an optical display device including the same. More particularly, the present invention relates to a module for an optical display, which secures improvement in productivity, processability, economic feasibility, and compensation for wide viewing angle while minimizing generation of curls, and an optical display device including the same.
  • a liquid crystal display is composed of a liquid crystal display panel including a liquid crystal layer, and a polarizing plate stacked on each of a light exit surface and a light incidence surface of the liquid crystal display panel and including a polarizer.
  • a vertical alignment liquid crystal layer or a horizontal alignment liquid crystal layer is used as the liquid crystal layer.
  • the horizontal alignment liquid crystal layer means a liquid crystal layer in which liquid crystal molecules are arranged parallel to a substrate for the liquid crystal display panel and are evenly aligned.
  • a liquid crystal display including the horizontal alignment liquid crystal layer can realize wide viewing angle through combination of many retardation layers.
  • the retardation layer may be realized in the form of a coating or a film.
  • a coating type retardation layer is advantageous in thickness reduction of the polarizing plate.
  • a film type retardation layer requires a roll-to-roll process in order to secure processability.
  • two retardation layers are used in the polarizing plate.
  • the second retardation film is bonded to the polarizing plate in a roll state via a bonding agent.
  • problems to be solved such as curls due to structural asymmetry with reference to the polarizer, introduction of foreign matter upon assembly, and the like, which cause increase in failure rate of the polarizing plate.
  • the background technique of the present invention is disclosed in Korean Patent Laid-open Publication No. 10-2005-0095974 and the like.
  • One aspect of the present invention relates to an optical display module.
  • Another aspect of the present invention relates to an optical display device.
  • the optical display device includes the optical display module according to the present invention.
  • the present invention provides an optical display device that secures improvement in productivity and processability.
  • the present invention provides an optical display device that secures good economic feasibility and good compensation for broad viewing angle.
  • the present invention provides an optical display device that secures good screen quality in an ultra-large screen.
  • the present invention provides an optical display device that minimizes generation of curls.
  • FIG. 1 is a conceptual view of an optical display module according to one embodiment of the present invention.
  • FIG. 2 shows transmittance of Examples 1 to 5 and Comparative Examples 1 to 5 in a black mode.
  • Equations A, B and C are represented by Equations A, B and C, respectively:
  • NZ ( nx ⁇ nz )/( nx ⁇ ny ) [Equation C]
  • nx, ny, and nz are indexes of refraction of a corresponding optical device in a slow axis direction, a fast axis direction and a thickness direction thereof at a measurement wavelength, respectively, and d denotes a thickness of the optical device (unit: nm).
  • X to Y means “greater than or equal to X and less than or equal to Y (X ⁇ and ⁇ Y)”.
  • the optical display module includes: an optical display panel; and a first polarizer, a first retardation layer and a second retardation layer sequentially stacked in the stated order.
  • the second retardation layer is disposed inside the optical display panel.
  • the first retardation layer and the first polarizer are sequentially stacked from a light exit surface of the optical display panel on the light exit surface of the optical display panel and outside the optical display panel.
  • the first retardation layer and the first polarizer may act as a viewer-side polarizing plate of the optical display device.
  • the optical display module allows improvement in processability and productivity while securing good economic feasibility and good compensation for broad viewing angle.
  • the optical display module according to the present invention secures good screen quality on an ultra-large screen. That is, the optical display module according to the present invention allows manufacture of a laminate of the first polarizer and the first retardation layer in a roll-to-roll process without a second retardation layer, thereby enabling reduction in thickness of the viewer-side polarizing plate and application to an ultra-large screen while securing improvement in productivity and processability.
  • the optical display module according to the present invention secures good compensation for wide viewing angle by controlling optical properties and the degrees of biaxiality of the first retardation layer and the second retardation layer within specific ranges of the present invention in placement of the second retardation layer, the first retardation layer and the first polarizer in the module.
  • FIG. 1 an optical display module according to one embodiment of the invention will be described.
  • the optical display module includes a first polarizer 20 , a first retardation layer 30 , a second retardation layer 40 , an optical display panel 10 , and a second polarizer 50 .
  • the second retardation layer 40 is disposed inside the optical display panel 10 .
  • the optical display module further includes a liquid crystal layer 60 inside the optical display panel 10 .
  • the first polarizer 20 , the first retardation layer 30 , and the second polarizer 50 are disposed outside the optical display panel 10 .
  • the first polarizer 20 is stacked on an upper surface of the optical display panel 10 (light exit surface of the optical display panel) to display an image through emission of light received from the optical display panel 10 therethrough.
  • the first polarizer 20 converts light or polarized light emitted from the optical display panel 10 into polarized light through linear polarization.
  • the first polarizer 20 may include a polarizer produced from a polymer film mainly consisting of a polyvinyl alcohol based resin.
  • the first polarizer may be prepared by dyeing the polymer film with iodine or dichroic dyes, followed by uniaxially stretching the polymer film in the MD (machine direction).
  • the first polarizer may be prepared through swelling, dyeing, stretching and crosslinking of a polyvinyl alcohol based film.
  • the first polarizer 20 may have a thickness of 30 ⁇ m or less, specifically greater than 0 ⁇ m to 30 ⁇ m, more specifically 2 ⁇ m to 20 ⁇ m, still more specifically 4 ⁇ m to 10 ⁇ m. Within this range, the first polarizer can be used in the polarizing plate.
  • the first polarizer 20 has a light absorption axis and a light transmission axis.
  • the light absorption axis of the first polarizer may correspond to the machine direction (MD) of the first polarizer and the light transmission axis of the first polarizer may correspond to the transverse direction (TD) of the first polarizer.
  • MD machine direction
  • TD transverse direction
  • liquid crystal molecules in a non-electric field state are aligned in a direction of +85° to +95°, specifically +90°, with reference to the light absorption axis (0°) of the first polarizer.
  • the polarizing plate can provide high front contrast to realize a clear image.
  • a polarizer protective film or a polarizer protective layer may be further stacked on the other side of the first retardation layer of the first polarizer 20 , that is, on an upper surface of the first polarizer 20 , between the first polarizer 20 and the first retardation layer 30 or between the first retardation layer 30 and the optical display panel 10 .
  • a functional coating layer such as a hard coating layer, an antiglare layer, an anti-fingerprint layer, an antireflective layer, and the like, may be further formed on an upper surface of the protective film or the protective layer stacked on the upper surface of the first polarizer 20 .
  • the polarizer protective film or the polarizer protective layer may be optically isotropic or anisotropic.
  • “optically isotropic” means that a corresponding film or layer has an in-plane retardation of 10 nm or less, for example, 0 nm to 10 nm, at a wavelength of 550 nm.
  • “optically anisotropic” means that a corresponding film or layer has an in-plane retardation of greater than nm, for example, greater than 10 nm to 15,000 nm, at a wavelength of 550 nm.
  • the polarizer protective film or the polarizer protective layer may provide an additional function to the polarizing plate through retardation according to optically isotropic or anisotropic properties.
  • the second retardation layer 40 is stacked on a lower surface of the first retardation layer 30 (light incidence surface of the first retardation layer) to provide an effect of compensation for broad viewing angle together with the first retardation layer.
  • the effect of compensation for broad viewing angle will be described below.
  • the second retardation layer 40 is disposed inside the optical display panel 10 . This structure allows elimination of an additional process for bonding the first retardation layer 30 to the second retardation layer 40 , thereby improving productivity and processability through simplification of a process of manufacturing the polarizing plate.
  • the second retardation layer 40 may be formed on the upper surface of the optical display panel, that is, on the light exit surface of the optical display panel.
  • the second retardation layer 40 may be formed of a non-liquid crystalline composition
  • the second retardation layer 40 is preferably formed by coating a liquid crystalline composition on a lower surface of a first substrate of the optical display panel described below, followed by curing the liquid crystalline composition in consideration of a liquid crystal layer that can be formed inside the optical display panel.
  • the second retardation layer may be formed by depositing an alignment layer on the lower surface of the first substrate and coating the liquid crystalline composition on the alignment layer, followed by curing the liquid crystalline composition.
  • the liquid crystalline composition may contain a reactive mesogen.
  • the reactive mesogen is a reactive liquid crystal monomer having a photo-polymerizable functional group and can realize phase retardation when cured through optical alignment, physical alignment or mechanical alignment.
  • the reactive mesogen may include a unit, such as a biphenyl group, a phenylbenzoate group, a phenylcyclohexane group, an azoxybenzene group, an azomethine group, a phenylpyrimidine group, a diphenylacetylene group, a diphenyl benzoate group, a bicyclohexane group, a cyclohexylbenzene group, a terphenyl group, and the like, as the mesogen group.
  • These units may further include a substituent group, such as a cyano group, an alkyl group, an alkoxy group, a halogen, and the like, at terminals thereof.
  • the liquid crystalline composition may further include a polymerizable liquid crystal monomer, a polymerizable monomer, a crosslinking agent, an initiator, and the like.
  • the reactive mesogen may be a typical reactive mesogen known to those skilled in the art. However, although the reactive mesogen can easily realize target retardation through alignment and curing, the reactive mesogen has a drawback of high price.
  • the second retardation layer 40 includes a positive A (+A) retardation layer having a degree of biaxiality of 0.9 to 1.1 at a wavelength of 550 nm (nx>ny nz, nx, ny, and nz being the indexes of refraction of the positive A retardation layer at a wavelength of 550 nm in the slow axis direction, the fast axis direction, and the thickness direction thereof, respectively).
  • the second retardation layer can provide the effect of compensation for broad viewing angle together with the first retardation layer while securing good economic feasibility through reduction in amount of the expensive reactive mesogen.
  • nx>ny nz and the degree of biaxiality may be achieved through adjustment of the material and alignment direction of the second retardation layer in formation of the second retardation layer.
  • the second retardation layer may have a degree of biaxiality of 0.95 to 1.05, more specifically 0.98 to 1.03, most specifically 1, at a wavelength of 550 nm. Within this range, the second retardation layer can provide the effect of compensation for broad viewing angle and can be easily formed.
  • the second retardation layer 40 may have an in-plane retardation of 70 nm to 120 nm, for example, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, 110 nm, 115 nm, or 120 nm, specifically 70 nm to 110 nm, more specifically 70 nm to 105 nm, at a wavelength of 550 nm.
  • the second retardation layer can secure compensation for broad viewing angle and thickness reduction of the optical display device while securing good economic feasibility through reduction in amount of the expensive reactive mesogen.
  • the second retardation layer 40 has a slow axis and a fast axis in the alignment direction thereof upon formation of the second retardation layer.
  • the slow axis of the second retardation layer 40 is tilted at an angle of ⁇ 5° to +5° with respect to the light absorption axis (0°) of the first polarizer.
  • the optical display panel can secure a high front contrast ratio to realize a clear image.
  • the slow axis of the second retardation layer 40 may be tilted at an angle of, for example, ⁇ 5°, ⁇ 4°, ⁇ 3°, ⁇ 2°, ⁇ 1°, 0°, +1°, +2°, +3°, +4°, or +5° with respect to the light absorption axis (0°) of the first polarizer and thus may be substantially parallel thereto.
  • the slow axis of the second retardation layer 40 may be tilted at an angle of +85° to +95°, specifically +90°, with reference to an alignment direction (0°) of liquid crystal molecules of the liquid crystal layer in a non-electric field state and thus may be substantially orthogonal thereto.
  • the second retardation layer 40 may have a thickness of 10 ⁇ m or less, specifically greater than 0 ⁇ m to 10 ⁇ m, or 0.5 ⁇ m to 2 ⁇ m.
  • the first retardation layer 30 is interposed between the first polarizer 20 and the second retardation layer 40 .
  • the first retardation layer 30 is stacked on a lower surface of the first polarizer 20 .
  • the first retardation layer 30 has a slow axis and a fast axis in an in-plane direction thereof.
  • the slow axis of the first retardation layer 30 is tilted at an angle of ⁇ 5° to +5° with respect to the light absorption axis (0°) of the first polarizer 20 .
  • the optical display module includes the first retardation layer and the second retardation layer to achieve compensation for broad viewing angle.
  • the second retardation layer is disposed inside the optical display panel and the first retardation layer is disposed outside the optical display panel such that the slow axis of the first retardation layer (MD of the first retardation layer) is tilted at an angle of ⁇ 5° to +5° with respect to the light absorption axis of the first polarizer (MD of the first polarizer), whereby a laminate of the first polarizer and the first retardation layer can be manufactured through bonding of the first retardation layer to the first polarizer provided in the form of a film in a roll-to-roll process without the second retardation layer, thereby enabling remarkable improvement in productivity and processability.
  • each of the first polarizer and first retardation layer is released from a wound roll and a bonding agent is placed between the first polarizer and first retardation layer, followed by curing the bonding agent. Accordingly, the method of manufacturing the laminate through roll-to-roll can achieve remarkable improvement in productivity and processability, as compared to formation of a coating layer for the retardation layer.
  • the slow axis of the first retardation layer is tilted at an angle of ⁇ 5°, ⁇ 4°, ⁇ 3°, ⁇ 2°, ⁇ 1°, 0°, +1°, +2°, +3°, +4°, or +5°, specifically ⁇ 3° to +3°, more preferably 0°, with respect to the light absorption axis (0°) of the first polarizer.
  • the slow axis of the first retardation layer is substantially in the same direction as the MD of the first retardation layer.
  • substantially in the same direction means that an angle between the slow axis of the first retardation layer and the MD of the first retardation layer is in the range of 0° to 5°, specifically 0° to 3°, more specifically 0°.
  • the slow axis of the first retardation layer may be the MD thereof and the fast axis of the first retardation layer may be the TD thereof.
  • the slow axis of the first retardation layer may be tilted at an angle of +85° to +95°, specifically +90°, with reference to the alignment direction of the liquid crystal molecules of the liquid crystal layer in a non-electric field state and thus may be substantially orthogonal thereto.
  • the optical display device can secure the effect of compensation for broad viewing angle.
  • the first retardation layer includes a positive B retardation layer having a degree of biaxiality of ⁇ 1 to ⁇ 0.2 at a wavelength of 550 nm (nz>nx>ny, nx, ny, and nz being the indexes of refraction of the positive B retardation layer at a wavelength of 550 nm in the slow axis direction, the fast axis direction, and the thickness direction thereof, respectively).
  • nz>nx>ny and the degree of biaxiality may be achieved through adjustment of the elongation ratio and the material of the first retardation layer in formation of the first retardation layer.
  • the first retardation layer may have a degree of biaxiality of, for example, ⁇ 1, ⁇ 0.9, ⁇ 0.8, ⁇ 0.7, ⁇ 0.6, ⁇ 0.5, ⁇ 0.4, ⁇ 0.3, or ⁇ 0.2, specifically ⁇ 1 to ⁇ 0.2, more specifically 31 0.8 to ⁇ 0.2, at a wavelength of 550 nm. Within this range, the optical display device can achieve compensation for broad viewing angle and thickness reduction thereof.
  • the first retardation layer 30 may have an in-plane retardation of 50 nm to 110 nm, for example, 50 nm, 55 nm, 60 nm, 65 nm, 70 nm, 75 nm, 80 nm, 85 nm, 90 nm, 95 nm, 100 nm, 105 nm, or 110 nm, specifically 50 nm to 100 nm, more specifically 50 nm to 90 nm, or 60 nm to 90 nm, at a wavelength of 550 nm. Within this range, the optical display device can achieve compensation for broad viewing angle.
  • the first retardation layer 30 may be a film formed of an optically transparent resin or may include a coating layer formed of a liquid crystalline composition or a non-liquid crystalline composition.
  • the first retardation layer is formed of a material having negative ( ⁇ ) birefringence.
  • the “material having negative birefringence” means a material having a slow axis (axis having an index of refraction (nx) in a direction in which the index of refraction in the in-plane direction becomes the maximum value) in a direction orthogonal to a stretching direction (or alignment direction) after stretching (or after alignment).
  • a resin having negative birefringence may have, for example, a chemical bond or a functional group, such as an aromatic group or a carbonyl group, which exhibits high anisotropy, introduced into side chains of the resin.
  • the resin having negative birefringence may include at least one selected from among an acrylic based resin, a styrene based resin, such as a non-modified styrene based resin and a modified styrene based resin, a maleimide based resin, and a fumaric acid ester based resin, without being limited thereto.
  • the “modified styrene based resin” is a styrene resin obtained through modification of a non-modified styrene resin with a typical functional group, which may be selected from among any typical functional groups well-known to those skilled in the art so long as the functional resin does not affect realization of negative ( ⁇ ) birefringence.
  • the first retardation layer may include a film produced through TD uniaxial stretching of a non-stretched film including the material having negative birefringence.
  • the slow axis of the first retardation layer becomes the MD of the first retardation layer, thereby facilitating manufacture of a viewer-side polarizing plate through a roll-to-roll process.
  • an angle between the light absorption axis of the first polarizer (MD of the first polarizer) and a stretching axis of the first retardation layer (TD of the first retardation layer) is in the range of +85° to +95°, specifically +90°, thereby minimizing generation of curls on the polarizing plate.
  • TD stretching may be realized by dry stretching or wet stretching through a single stage or multiple stages by a typical method known to those skilled in the art.
  • a TD elongation ratio of the first retardation layer may be suitably adjusted such that the first retardation layer reaches the degree of biaxiality within the above range.
  • the first retardation layer 30 may have a thickness of greater than 0 ⁇ m to 80 ⁇ m, specifically 20 ⁇ m to 80 ⁇ m.
  • the slow axis of the first retardation layer may be tilted at an angle of +85° to +95°, specifically +90°, with reference to the alignment direction (0°) of the liquid crystal molecules of the liquid crystal layer in a non-electric field state and thus may be substantially orthogonal thereto.
  • an adhesive layer, a bonding layer or an adhesive/bonding layer may be formed between the first polarizer 20 and the first retardation layer 30 to bond the first polarizer to the first retardation layer.
  • the bonding layer may be formed of a water-based bonding agent and/or a photocurable bonding agent, without being limited thereto.
  • the adhesive layer may be formed of a (meth)acrylic adhesive, without being limited thereto.
  • the first polarizer may be bonded to the first retardation layer through a roll-to-roll process, thereby facilitating treatment of the adhesive layer, the bonding layer or the adhesive/bonding layer.
  • the adhesive layer, the bonding layer or the adhesive/bonding layer may be formed on a lower surface of the first retardation layer, whereby the polarizing plate (for example, the viewer-side polarizing plate including the first polarizer and the first retardation layer can be stacked on the optical display panel.
  • the polarizing plate for example, the viewer-side polarizing plate including the first polarizer and the first retardation layer can be stacked on the optical display panel.
  • the optical display panel 10 includes an image display medium.
  • the optical display panel 10 may include a liquid crystal layer 60 as the image display medium.
  • the present invention is not limited thereto.
  • the liquid crystal layer 60 may include liquid crystal molecules in a horizontal alignment (HA) mode in a non-driven state.
  • the liquid crystal molecules may be evenly aligned parallel to a flat surface of a first substrate or a second substrate.
  • the liquid crystal layer may adopt an in-plane switching (IPS) mode or a fringe field switching (FFS) mode as the horizontal alignment (HA) mode.
  • IPS in-plane switching
  • FFS fringe field switching
  • the liquid crystal molecules may be nematic liquid crystals or sematic liquid crystals, without being limited thereto.
  • the liquid crystal molecules may employ positive (+) and negative (+) dielectric anisotropy, without being limited thereto.
  • the optical display panel 10 may include at least one substrate in order to allow the image display medium including the liquid crystal layer 60 and the second retardation layer 40 to be easily included in the optical display panel.
  • the optical display panel may include a first substrate 11 and a second substrate 12 facing the first substrate 11 .
  • Each of the second retardation layer 40 and the liquid crystal layer 60 may be disposed between the first substrate 11 and the second substrate 12 .
  • the first substrate 11 is disposed on the light exit surface of the optical display panel, and functional optical elements for driving the optical display panel and/or image display, such as a color filter, a black matrix, and the like, may be formed on an upper or lower surface of the first substrate.
  • the second substrate 12 may be disposed on the light incidence surface of the optical display panel.
  • a switching element for controlling electrical and optical properties of liquid crystals may be formed on an upper surface of the second substrate.
  • Each of the first substrate 11 and the second substrate 12 may be formed of a glass substrate, a transparent plastic film, or a transparent plastic substrate, without being limited thereto.
  • the optical display panel includes the second substrate 12 , the liquid crystal layer 60 , the second retardation layer 40 , and the first substrate 11 , which are sequentially stacked in the stated order, in which both the liquid crystal layer 60 and the second retardation layer 40 may be disposed in a space defined by the second substrate 12 and the first substrate 11 .
  • the second retardation layer may be directly formed on a lower surface of the first substrate.
  • directly formed means that neither adhesive layer, nor a bonding layer, nor an adhesive/bonding layer is formed between the first substrate and the second retardation layer.
  • the liquid crystal layer 60 is formed on a lower surface of the second retardation layer 40 such that the first polarizer 20 , the first retardation layer 30 , the second retardation layer 40 , and the liquid crystal layer 60 are sequentially stacked in the stated order in the optical display panel.
  • the second retardation layer 40 may be spaced apart from the liquid crystal layer 60 . With this structure, the second retardation layer 40 does not affect the alignment direction or the driving direction of the liquid crystal molecules in the liquid crystal layer 60 .
  • the second polarizer 50 is disposed at the other side of the first polarizer 20 (on the light incidence surface of the optical display panel) with reference to the optical display panel 10 .
  • the second polarizer 50 may include a polarizer produced from a polymer film mainly consisting of a polyvinyl alcohol resin.
  • the second polarizer may be prepared by dyeing the polymer film with iodine or dichroic dyes, followed by uniaxially stretching in the MD (machine direction).
  • the second polarizer may be prepared through swelling, dyeing, stretching and crosslinking of a polyvinyl alcohol film.
  • the second polarizer 50 may have a thickness of greater than 0 ⁇ m to 30 ⁇ m, specifically 2 ⁇ m to 20 ⁇ m, more specifically 4 ⁇ m to 10 ⁇ m. Within this range, the second polarizer can be used in the polarizing plate.
  • the second polarizer 50 has a light absorption axis and a light transmission axis.
  • the light absorption axis of the second polarizer may correspond to the machine direction (MD) thereof and the light transmission axis of the second polarizer may correspond to the transverse direction (TD) of the second polarizer.
  • the light absorption axis of the second polarizer 50 may be tilted at an angle of +85° to +95°, specifically +90°, with reference to the light absorption axis) (0°) of the first polarizer and thus may be substantially orthogonal thereto.
  • the light absorption axis of the second polarizer may be in the same direction as the short direction of the optical display panel.
  • an optically isotropic or anisotropic polarizer protective film or an optically isotropic or anisotropic polarizer protective layer may be further formed on at least one surface of the second polarizer 50 .
  • the optically isotropic or anisotropic polarizer protective film and the optically isotropic or anisotropic polarizer protective layer are the same as those described above.
  • an adhesive layer, a bonding layer or an adhesive/bonding layer may be formed on an upper surface of the second polarizer 50 or between the second polarizer 50 and the polarizer protective film or the polarizer protective layer to allow a polarizer (for example, a light-source side polarizer) including the second polarizer to be stacked on the optical display panel therethrough.
  • a polarizer for example, a light-source side polarizer
  • the second polarizer or the polarizing plate including the same may be omitted depending upon the kind of image display medium in the optical display panel.
  • the optical display device includes an optical display module according to one embodiment of the present invention.
  • the optical display device may include a liquid crystal display device, without being limited thereto.
  • the liquid crystal display device may include an optical display module, a backlight unit, and the like.
  • the backlight unit may be disposed outside the first polarizer or outside the second polarizer.
  • the backlight unit may be manufactured by adopting typical optical elements, such as a light source, a light guide plate, an optical sheet, and the like, well-known to those skilled in the art.
  • a polarizer having a light transmittance of 43% was prepared by stretching a polyvinyl alcohol film (PS #60, pre-stretching thickness: 60 ⁇ m, Kuraray Co., Ltd.) to 6 times an initial length thereof in the MD in an aqueous solution of iodine at 55° C.
  • the prepared polarizers were used as a first polarizer and a second polarizer.
  • Each of the first polarizer and the second polarizer has a light absorption axis in the same direction as the MD of each of the first polarizer and the second polarizer.
  • a first retardation layer exhibiting phase retardation as listed in Table 1 was manufactured through TD-uniaxial stretching of a non-stretched film including a negative-birefringence resin (modified styrene based resin) at a predetermined elongation ratio.
  • the slow axis of the first retardation layer is the MD of the first retardation layer.
  • a viewer-side polarizing plate was prepared by bonding the first retardation layer to a lower surface of the first polarizer corresponding to a light incidence surface of the first polarizer through a roll-to-roll process using a bonding agent, with the absorption axis of the first polarizer disposed parallel to the slow axis of the first retardation layer.
  • a source-side polarizing plate was prepared by bonding a triacetylcellulose film to a light exit surface of the second polarizer.
  • a module was prepared by stacking the viewer-side polarizing plate on a light exit surface of a liquid crystal panel (including an FFS liquid crystal layer) including the second retardation layer having phase retardation as listed in Table 1 inside the liquid crystal panel while stacking the light source-side polarizing plate on a light incidence surface of the liquid crystal panel.
  • the viewer-side polarizing plate includes the first retardation layer and the first polarizer sequentially stacked on the liquid crystal panel.
  • the light absorption axis of the first polarizer was orthogonal to the light absorption axis of the second polarizer.
  • the light absorption axis of the first polarizer, the slow axis of the first retardation layer, and the slow axis of the second retardation layer were parallel to one another.
  • each of the light absorption axis of the first polarizer, the slow axis of the first retardation layer, and the slow axis of the second retardation layer was orthogonal to an alignment direction of liquid crystal molecules in a non-electric field state in the panel.
  • Each module was prepared in the same manner as in Example 1 except that retardation of each of the first retardation layer and the second retardation layer was changed as listed in Table 1.
  • a first polarizer and a second polarizer were prepared in the same manner as in Example 1.
  • a viewer-side polarizing plate was prepared by sequentially stacking a first retardation layer and a second retardation layer to a lower surface of the first polarizer, as listed in Table 1.
  • a module was manufactured by stacking the viewer-side polarizing plate on a light exit surface of a liquid crystal panel (including an FFS liquid crystal layer) while stacking the light source-side polarizing plate on a light incidence surface of the liquid crystal panel. Assuming that the light absorption axis of the first polarizer is 0° in the viewer-side polarizing plate, the slow axis of the first retardation layer is orthogonal to the slow axis of the second retardation layer.
  • Each module was prepared in the same manner as in Example 1 except that the structure of each of the first retardation layer and the second retardation layer was changed as listed in Table 1.
  • a module was prepared in the same manner as in Example 1 except that the structure of the first retardation layer was changed, as listed in Table 1, and a Bo retardation layer having NZ of 0.8 at a wavelength of 550 nm in Table 1 (nx>nz>ny, nx, ny, and nz being the indexes of refraction of the Bo retardation layer at a wavelength of 550 nm in the slow axis direction, the fast axis direction, and the thickness direction thereof, respectively) was used as the second retardation layer.
  • a module was prepared in the same manner as in Example 1 except that the structure of the first retardation layer was changed, as listed in Table 1, and a ⁇ B retardation layer having NZ of 1.2 at a wavelength of 550 nm in Table 1 (nx>nz>ny, nx, ny, and nz being the indexes of refraction of the ⁇ B retardation layer at a wavelength of 550 nm in the slow axis direction, the fast axis direction, and the thickness direction thereof, respectively) was used as the second retardation layer.
  • Retardation of each of the first retardation layer and the second retardation layer was measured at a wavelength of 550 nm using an AxoScan spectrometer.
  • the optical display module according to the present invention includes a viewer-side polarizing plate produced through a roll-to-roll process, thereby enabling improvement in processability and productivity while securing good compensation for broad viewing angle.
  • the module of Comparative Example 1 including the laminate of the first polarizer, the +A layer and the +B layer as the viewer-side polarizing plate had low processability and productivity while providing poor compensation for broad viewing angle due to difficulty in fabrication of the viewer-side polarizing plate through a roll-to-roll process.
  • the module of Comparative Example 2 not having the structures of the first retardation layer and the second retardation layer according to the present invention had low processability and productivity while providing poor compensation for broad viewing angle due to difficulty in fabrication of the viewer-side polarizing plate through a roll-to-roll process, and the modules of Comparative Examples 3 to 5 could not be used due to poor compensation for broad viewing angle.

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  • Physics & Mathematics (AREA)
  • Nonlinear Science (AREA)
  • Mathematical Physics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Liquid Crystal (AREA)
  • Polarising Elements (AREA)
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KR1020200131471A KR20220048382A (ko) 2020-10-12 2020-10-12 광학표시장치용 모듈 및 이를 포함하는 광학표시장치
PCT/KR2021/013797 WO2022080757A1 (ko) 2020-10-12 2021-10-07 광학표시장치용 모듈 및 이를 포함하는 광학표시장치

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